The visual quality of the light
To create good quality visual solutions, we at Fagerhult are constantly working to develop our optimisation methods.
A solution for every application
It is always important to tailor each solution to the specific application. However, a measure that solves one problem can cause another to arise, such as reduced efficiency, a negative impact on light distribution or an effect on average luminance and UGR. Several factors therefore need to be taken into account. It’s not uncommon to need to find a good compromise.
Light measurements provide us with valuable information about our luminaires. These are used to verify that light planning and requirements in line with standards are being met. We also measure the efficiency of the luminaires.
Key points to consider when evaluating visual quality (Light) include:
- The luminaire must be set to an appropriate light output.
- The luminaire must be installed in the manner in which it is intended to be used, for example:
- a recessed luminaire must be installed in a suspended ceiling
- a pendant luminaire must be positioned at an appropriate distance from a tabletop
- a bollard must be installed at the correct height above the ground. - Will the luminaire be placed near a wall?
- Is the right surface being lit? Asphalt, industrial flooring, etc.?
Simulation
By simulating a visual problem, we can optimise the solution, minimise the problem and/or avoid it entirely. Simulation is an important tool in the development of our optics. However, it can never fully replace prototypes when it comes to ensuring high visual quality.
Examples of what we want to avoid include:
Uønskede skygger
I tilfælde af uønskede skygger forårsaget af optikken skal kontrasten mellem mørke og lyse områder forbedres. Mulige tiltag omfatter:
- Skabe en mere ensartet lysfordeling ved at sprede lyset
- Øge antallet af lyspunkter/LED’er
- Optimere optikken for at opnå et mere homogent lysmønster
I de fleste tilfælde er en kombination af disse løsninger nødvendig for at opnå et acceptabelt resultat.
Multiple skygger
I de fleste anvendelser, såsom kontormiljøer, ønsker vi at undgå skygger fra objekter. Hvis afstanden mellem LED’erne er for stor, vil hvert lyspunkt skabe sin egen skygge, og jo større afstanden er, jo mere markant bliver kontrasten mellem skyggerne.
En måde at undgå flere skygger på er ved at bruge en specialtilpasset raster, for eksempel Beta Opti Nano. Ved at tilføje flere lyspunkter mellem hver celle i rasteret, kombineret med en diffuserende film og lamellernes design, minimeres forekomsten af multiple skygger samtidig med, at en god effektivitet og blændingskontrol opretholdes. Samlet set resulterer dette i blødere skygger og en mere ensartet visuel effekt.
Color over Angle (CoA)
Med introduktionen af LED opstod der nye udfordringer, såsom Color over Angle (CoA). Dette beskriver, hvordan den opfattede farve fra en lyskilde ændrer sig afhængigt af betragtningsvinklen.
Billedet til venstre viser et skematisk tværsnit af en LED. Den blå firkant repræsenterer chippen, hvor lyset genereres, og den er blå i farven. Det gule område er et fosforlag, der omdanner det blå lys til et bredere farvespektrum, så det fremstår hvidt for det menneskelige øje. Da lyset bevæger sig forskellige afstande gennem fosforlaget, varierer dets farve med udstrålingsvinklen. Dette kan resultere i farveforskydninger – som gullige eller blålige nuancer – på overflader, der er beregnet til at fremstå hvide.
An unevenly lit surface
We want to avoid illuminated surfaces being unevenly lit, such as in the example below, where a bollard is causing irregular streaks of light. Even if all requirements are met in theory – and in Dialux – there may still be shortcomings in the visual expression. There are many ways to reduce this or prevent it from happening. For example, it is possible to soften the light distribution using diffuse films or surfaces.
